1. Field of the Invention
The present invention relates to an apparatus for measuring and assisting in the alignment and repair of damaged or potentially damaged structural members. The present invention has particular application to the structural measurements of damaged and repaired automobiles.
2. Background of the Prior Art
In the manufacture of automobiles, it is common practice to provide specific datum points in the structure of the vehicle during manufacture, for use in checking the dimensional accuracy of the finished product. These datum points can take various forms such as holes in the chassis, male and female threaded members such as bolt heads, nuts or studs, and other formations such as pins, lugs and suspension mounting points.
These datum points may be oriented in vertical or horizontal planes, or at intermediate angles. They also vary significantly from model to model according to various design parameters and practical convenience. In all cases, however, they are accurately positioned in known locations and the design specification of each vehicle normally includes a table of dimensions which correlate the various datum points.
In the case of damaged vehicles, these datum points can be used to define a reference datum plane using datum points from an undamaged section of the vehicle. This datum plane can then be used as a reference for determining the deviation from vehicle specifications of the reference points on the damaged section of the vehicle, or to ensure that a damaged vehicle has been sufficiently repaired with reference to specifications.
Numerous types of known vehicle measurement apparatus purport to provide a means for determining a deviation of a datum point from specification, to facilitate the evaluation and repair of damaged or potentially damaged vehicles.
One such apparatus is discussed in U.S. Pat. No. 6,769,192 issued on Aug. 3, 2004 to Johansson et al describes an extension ruler having a built in measuring device. The built in measuring device incorporates a tape extending from one end of the extension ruler to the other end, where the tape is wound on a drum spring. A digital display of a measurement is provided by detecting the rotation of the drum via a light source and photo diode. The measuring device further includes a spirit level to allow quick and normalized measuring, such that the spirit level represents an approximation of the datum plane.
One problem with such prior art devices is due to the use of a spirit level. A supposition in the prior art is that the vehicle being measured is oriented parallel to the natural horizontal plane defined by the spirit level. In practice, a vehicle may further, or alternatively, be oriented to have a pitch and/or a roll with respect to the natural horizontal plane indicated by a spirit level. The actual datum plane of the vehicle, therefore, may have a pitch such that the vehicle is longitudinally inclined with respect to the natural horizontal plane. The vehicle may further be oriented to have a roll such that the vehicle is laterally inclined with respect to the natural horizontal plane. For this reason, measurements taken using a spirit level may incorporate errors due to the pitch and/or roll of the reference datum plane with respect to the natural horizontal plane indicated by the spirit level.
It would, therefore, be advantageous to provide a means for ensuring that measurements are made parallel to the reference datum plane of the vehicle so as to increase measurement accuracy and minimize measurement errors with respect to prior art devices.
Another problem with such prior art devices is that a user is required to manually record measurements, for example, into a database. Although the prior art device discussed herein provides a digital display of a measurement, a user must still separately record such measurements in a database or record sheet.
It would, therefore, be advantageous to provide a means for allowing digital recordation of measurements displayed by the device, so as to eliminate the need for manual recordation and data entry.
It would, additionally be advantageous to provide a measurement device that is simple in design and operation as compared to the prior art devices.
It is an object of the present invention to solve these and additional problems of the prior art.